Fixed islands in other worlds are not detected correctly (#1426)

src/main/java/com/bgsoftware/superiorskyblock/core/IslandPosition.java

@@ -3,17 +3,19 @@
 import com.bgsoftware.superiorskyblock.SuperiorSkyblockPlugin;
 import org.bukkit.Location;
 
+import javax.annotation.Nullable;
 import java.util.Objects;
 
 public class IslandPosition {
 
     private static final SuperiorSkyblockPlugin plugin = SuperiorSkyblockPlugin.getPlugin();
 
+    @Nullable
     private final String worldName;
     private final int x;
     private final int z;
 
-    private IslandPosition(String worldName, int x, int z) {
+    private IslandPosition(@Nullable String worldName, int x, int z) {
         this.worldName = worldName;
         this.x = x;
         this.z = z;
@@ -27,15 +29,15 @@ public static IslandPosition of(String worldName, int locX, int locZ) {
         int radius = plugin.getSettings().getMaxIslandSize() * 3;
         int x = (Math.abs(locX) + (radius / 2)) / radius;
         int z = (Math.abs(locZ) + (radius / 2)) / radius;
-        return new IslandPosition(worldName, locX < 0 ? -x : x, locZ < 0 ? -z : z);
+        return new IslandPosition(plugin.getProviders().hasCustomWorldsSupport() ? worldName : null, locX < 0 ? -x : x, locZ < 0 ? -z : z);
     }
 
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
         IslandPosition that = (IslandPosition) o;
-        return x == that.x && z == that.z && worldName.equals(that.worldName);
+        return x == that.x && z == that.z && Objects.equals(worldName, that.worldName);
     }
 
     @Override